1. Field of the Invention
The present invention relates to a component built-in module in which an electronic component such as a semiconductor and/or a circuit component is provided inside an electric insulation layer, and to a method for manufacturing the same.
2. Related Background Art
Recently, following the tendency of electronic devices toward high performance and compact size, it is increasingly demanded to achieve high density and improved function of circuit components. It also is demanded to provide a circuit-component-mounted module suitable for high density and improved performance. To mount circuit components at a higher density, wiring patterns are complicated increasingly, and hence, there is a tendency of wiring boards toward multi-lamination.
In the case of conventional glass-epoxy substrates, multi-lamination is achieved with a through hole structure that is obtained by drilling. This structure has high reliability, but wiring patterns provided thereon are limited since wiring patterns in different layers are connected using through holes. Furthermore, a semiconductor or a circuit component cannot be mounted at an area on a surface of the wiring board where the through hole is provided, and therefore, it is not suitable for high-density component-mounting.
Therefore, as a method for achieving high densification of circuitry, a multi-layer wiring board utilizing electric connection by inner vias is used also. The inner via connection allows the wiring patterns between large scale integrated circuits (LSIs) and components to be connected over the shortest distances, and also provides only necessary connections between wiring pattern layers, thereby facilitating the circuit component mounting. Furthermore, by incorporating circuit components in a wiring board, the component mounting efficiency is improved further.
However, the incorporation of circuit components and the connection of the same through inner vias may have a problem in reliability. The reliability of the inner via connection is influenced significantly by the ratio of a height of an inner via to a diameter thereof (i.e., aspect ratio=height/diameter). In the case where a circuit component is incorporated in a wiring board, an electric insulation layer having a height greater than a height of the circuit component is required, thereby necessarily causing an inner via to have a greater height. Therefore, to improve the connection reliability, it is necessary to increase the diameter of an inner via. However, an increase in the diameter leads to a decrease in the mounting density.